This invention relates to conveyor systems, and particularly to devices for conveying objects from one input conveyor to one of at least two output conveyors.
In the movement of a large number of objects by conveyor, it is common to have objects, which are proceeding on a single conveyor, that are desired to be directed to more than one output conveyor. For example, in the field of transporting of parcels and packages, the packages unloaded from an incoming single truck or other vehicle at a sorting facility conventionally have a large number of different destinations. The individual packages must be directed, within such a central sorting facility, to one of a large number of different outgoing trucks or other vehicles, depending on the ultimate destination of the package. Generally, this will be achieved by having various points where an object on a conveyor may be switched to one of at least two outgoing conveyors.
Directing each parcel or package individually requires that an apparatus for directing packages be able to direct one package to one output conveyor and direct the next succeeding package to a different output conveyor. The time necessary for the apparatus to change its orientation to achieve this result is referred to as the "cycle time." In handling a large number of packages, it is desirable that the packages move as quickly as possible and as close together as possible on the conveyors. This provides high throughput of packages on the conveyors. In order to have a high throughput, an apparatus must have a short cycle time.
It is important in the field of shipping parcels and packages that the parcels and packages be subjected to as little jarring and sudden changes of direction as possible. Sudden changes in direction or jarring can cause fragile or poorly-packed items to break. In addition, repeated jarring over the course of a journey of a parcel or package may cause packing material to become dislodged and fail to be properly oriented for protection of the contents of the package.
In a large facility for sorting of packages, space is at a premium. In particular, horizontal floor area is at a premium in such facilities. Consequently, an apparatus for directing a package from a single input conveyor to two or more output conveyors, while using a minimum of floor area, is desirable. In particular, an apparatus that permits the output conveyors to be vertically disposed is quite advantageous.
It is known to provide an apparatus where an intermediate conveyor is provided between a discharge end of an input conveyor and a receiving end of at least two output conveyors, the intermediate conveyor being hingedly mounted adjacent the discharge end of the input conveyor, whereby the intermediate conveyor may rotate so as to be aligned with the receiving end of any one of the at least two output conveyors. Such an apparatus is disclosed, for example, in U.S. Pat. No. 3,358,831. However, this type of apparatus is not particularly well suited to use in high-volume parcel and package sorting applications. If the intermediate conveyor is discharging a package onto a lower output conveyor, and begins to move before the parcel or package has completely cleared the discharge end of the intermediate conveyor, damage to the parcel or package may result. The trailing edge of the parcel or package will be lifted above the output conveyor, and will fall back down with a sharp impact when it clears the discharge end of the intermediate conveyor. If the parcel or package remains on the intermediate conveyor while the intermediate conveyor is moving, the package may be smashed into the lower side of the next highest output conveyor. Thus, the discharge end of the intermediate conveyor must be maintained adjacent to one of the output conveyors until each article is completely clear of the discharge end of the intermediate conveyor. This requirement results in a relatively long cycle time. In addition, parcels and packages may be as much as two to three feet in height. Thus, at least two to three feet must be provided between the lower side of one output conveyor and the upper side of the next-lowest output conveyor. As a result, the intermediate conveyor must be flipped through a relatively long distance. The requirement to flip through long distance results in a relatively high cycle time.